Background: The optimal treatment of localized prostate cancer (PCa) remains controversial. We compared long-term survival among men who underwent radical prostatectomy (RP), brachytherapy (BT), external beam radiation therapy (EBRT), primary androgen deprivation therapy (PADT), or monitoring (AS/WW) for localized PCa. Methods: Within the CaPSURE registry, we analyzed 12,062 men with localized PCa. PCa risk was assessed using the Stephenson preoperative nomogram and the Cancer of the Prostate Risk Assessment (CAPRA) score. Multivariable analyses were performed to compare prostate cancer-specific mortality (PCSM) and all-cause mortality (ACM) by primary treatment, adjusting for age and case-mix. An inverse probability weighted regression adjustment was used to reflect propensity for treatment assignment and any imbalances in censoring. Results: 6,357 men (53%) underwent RP, 1,351 (11%) BT, 1,716 (14%) EBRT, 1,605 (13%) PADT, and 1,033 (9%) AS/WW. During the 18-year follow-up period, 514 men died from PCa. Adjusting for clinical CAPRA score, the hazard ratios for PCSM relative to RP were 1.46 (95% CI, 1.00-2.12, p=0.050) for BT, 1.81 (95% CI, 1.43-2.30, p<0.001) for EBRT, 2.77 (95% CI, 2.18-3.51, p<0.001) for PADT, and 1.81 (95% CI, 1.23-2.66, p=0.003) for AS/WW. The greatest difference in PCSM between treatment modalities was observed for high-risk patients. Adjusting for age, comorbidity, and clinical CAPRA score, the hazard ratios for ACM were 1.46 (95% CI, 1.28-1.67) for BT, 1.38 (95% CI, 1.24-1.54) for EBRT, 1.89 (95% CI, 1.67-2.13) for PADT, and 1.60 (95% CI, 1.39-1.84) for AS/WW compared to RP (all p<0.001). Additional analyses using 100-Stephenson score or Fine-Gray competing risks analysis demonstrated similar results. Conclusions: In a large, prospective cohort of men with localized PCa, after adjustment for age and comorbidity, risk of PCSM and ACM was lowest after RP. Mortality was significantly higher after EBRT and AS/WW, and highest after PADT. RP should be offered as part of the management paradigm for high-risk disease, AS/WW should be preferred for most low-risk PCa.